doc: copyedit COLLABORATOR_GUIDE.md
doc: copyedit COLLABORATOR_GUIDE.md

PR-URL: https://github.com/nodejs/io.js/pull/1964
Reviewed-By: Alex Kocharin <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@kocharin.ru>
Reviewed-By: Johan Bergström <3e38e5ce4283f06de4b83ad13af081abc5e16740@bergstroem.nu>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node